Subaru Spark Plugs Questions

A spark plug is a key component in an internal combustion engine which ignites the compressed fuel/air mixture in a piston and provides it with momentum. Spark plugs are linked to the distributor through a pair of electrodes. The distributor is the source of the electrical power which creates the spark.

They are robust elements which rarely fail but when they do, they can be the cause of a host of engine problems. Experts on Subaru cars are often called upon to provide solutions to spark plug problems. Read below some questions Experts have answered and helped provide solutions.

Is it possible for a spark plug wire to come off the plug on a Subaru engine

If the plug wires are fairly old they can work their way loose with engine vibration. This is even more probable if the rubber insulation has hardened and oil seeps into the plug tube. If the plug wires are relatively new and fit well on the plugs they are unlikely to work their way off. A spark plug which has not been properly tightened can also unscrew itself.

Is there an easier way to change the spark plugs on a Subaru Legacy?

The boot which sits on top of the plug is connected to the plug wire. This will somehow have to be cut away or broken off to remove the plug. This means that the plug wire must be replaced. The best way to replace spark plugs is to remove the water reservoir and air filter first to provide more access. Even then it is difficult to reach the plugs and the exhaust might have to be dropped. When this is done the dog bone/motor mount nuts can be removed with the engine raised which will provide easier access.

Another way is to lever the plug wire off the valve cover with a pair of long-handled long nose pliers. When the boot is removed from the wire, the top of the plug can be broken off by tapping it with a small punch and hammer. This should reach the bottom threaded portion of the plug which can then be unscrewed.

How can the plug wires on a Subaru keep working their way off resulting in a misfire?

Sometimes the wires come off the spark plugs even if both are new. The spark plugs on this engine are located in such an awkward position which makes it extremely difficult to reach them. There is no alternative but to wiggle the plug wires till hearing them snap in place which signifies they are properly secured to the plugs. It might be difficult to do this with aftermarket plugs which are a bit short in the boot. This situation will not arise with a factory set which is well worth the additional cost.

A Subaru Outback has been fitted with a second-hand motor but only one spark plug fires. How can one get all spark plugs to fire?

Replace the crank and cam sensors and check that the timing belt is properly aligned. This problem is frequently encountered if the sensors are weak or the timing belt is misaligned.

What can be done to a Subaru WRX which misfires consistently on the first cylinder? The ignition coil and spark plugs are new.

These engines are known for arcing of the spark plug wires within the boot. Remove the spark plug wire from the first cylinder. See if there are white marks inside the boot where it sits on the plug. If white marks are visible then the spark plug wire will have to be replaced.

What are the best spark plugs to install on a Subaru ej20G, and what is the recommended plug gap for peak performance?

The best spark plugs for this car are the NGK PFR7B. The recommended gap is 0.8mm and the torque should be 13-17 lb ft (18-24 Nm).

Spark plugs are a key part of an engine largely responsible for effective performance. It is critical to keep them in perfect working order at all times. Platinum spark plugs, which are the newest innovation, need far less maintenance and offer a lifespan of as much as 100,000 miles. Since engine performance is so closely linked to the way its spark plugs behave, it is always advisable to consult an Expert on spark plug-related issues.

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Related questions

I have a 2005 Subaru Outback XT. Check engine code 0302 in cylinder #2. I have switched the the coil packs and fuel injectors from another cylinder and no change. Can you please advise as what to do next. Frank

I have a 2014 Subaru outback. one of the four spark plugs is not grab-able with a spark plug socket. It does not appear that the socket is seating on the plug as you do not get that click feel when inserting the socket onto the plug. The socket works fine with the other three plugs and I was already able to remove and replace them. Luckily this is the most accessible plug, the one right by the air filter. When I try to look down the spark plug hole I do not see anything unusual, but can imagine that there may be a rubber grommet on the plug. This is based on advice I gleaned from internet searches. I tried grabbing the rubber grommet with a coat hanger with not luck and even tried a red hot screwdriver to burn the rubber, but it did not seem to change anything both in the mirror I use to observe down the plug hole or in the feel of the socket when inserting it. This was a new car purchase and this was the first time I tried to change the plugs. Whatever is wrong is something that happened during the original assembly. Any suggestions?

I have problems with the spark in spark plugs there is no spark in my 2005 subaru 3.0 JA: How many miles are on the car? When was the last time the plugs were changed? Customer: good this subaru was installed a motor when work was installed but with a problem in spark plug 4 was located the fault because it was the harness that had a loose wire after that and did not want to start my question is if there is a fuse that sends current and q has been melted or some relays when the spark plugs were being installed, the extension was stuck with the power cord of the battery JA: What is the model of your '05 Subaru? Customer: Yes JA: Are you fixing your vehicle yourself? What have you tried so far? Customer: Ok then I checked fuse switch crank shaft position sensor, CAM position sensor but I only have gasoline and no spark in spark plugs JA: Anything else you want the mechanic to know before I connect you? Customer: I do not think it's all I also got a computer but the problem still

Hello Gary I am wondering which spark plugs would be best for my wrx. Just bought the car and havent had it on dyno. Have a bigger turbo aith pink sti injectors, I'm guessing right around 300 hp. Not sure whether to go with iridium or platinum

had a misfire in cylinder 6 I have replaced all spark plugs in all cylinders as well as the replaced the Ignition coil for cylinder 6. However it is still pulling a p0306 code on that cylinder. The car is also shaking and vibrating. JA: How many miles are on the car? Is it a steady misfire? Or random? Customer: 144,000 JA: What is the make/model/year of your car? Customer: 2009 Subaru Legacy 3.0R JA: Are you fixing your Legacy yourself? What have you tried so far? Customer: Yes I am, I have Just replaced the Spark plugs, and the ignition coil. JA: Anything else you want the mechanic to know before I connect you? Customer: I cannot think of anything else yet.

My boyfriend changed my spark plugs in my Subaru and now my car won't even start JA: How many miles are on the car? When did you last change the plugs? Customer: 210 and I just got the car from an auction about 4 months ago and they don't tell you anything on it so I decided to change them JA: What is the model/year of your Subaru? Customer: *210 hundred thousand miles JA: What year is your Subaru? Customer: It's an impreza 2009 non turbo JA: Are you fixing your Impreza yourself? What have you tried so far? Customer: Just the spark plugs my boyfriend did that's all JA: Anything else you want the mechanic to know before I connect you? Customer: No

i have just bought a 1998 foster and the spark plug lead on the passengers keeps on jumping off you drive about 1klm on the dam thing is off ,i have swaped the leads and it did not work JA: What is the model of your '98 Subaru? Customer: i think the top off the range as it has every thing in it JA: Are you fixing your vehicle yourself? What have you tried so far? Customer: yes JA: Anything else you want the mechanic to know before I connect you? Customer: i have swaped the leads over but it did not work

spark plug stuck in engine. 2000 model JA: How many miles are on the car? Is it an automatic or a manual transmission? Customer: manual 300,000 km JA: What is the model of your '00 Subaru? Customer: it's my daughter's, not sure of the model JA: Are you fixing your vehicle yourself? What have you tried so far? Customer: Just looked at it. Friend says try soak it with WD40 JA: Anything else you want the mechanic to know before I connect you? Customer: no

2002 Subaru Outback, 4 cyl. 281,000 miles. New spark plugs, (this happened before changing plugs), new air filter, fairly new gas filter. On occasion, after I have driven the car for a while and it is at normal temperature, and then I stop and park the car for a short duration, like 10-15 minutes, the car will crank but not start. If I let it set for 10-20 minutes it will start right up.